package com.x.scratch.util;

import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;

public class MD5Util {
    private static final String[] hexDigits = {"0", "1", "2", "3", "4", "5", "6", "7", "8", "9", "a", "b", "c", "d", "e", "f"};

    private static String byteArrayToHexString(byte[] b) {
        StringBuffer resultSb = new StringBuffer();
        for (int i = 0; i < b.length; i++) {
            resultSb.append(byteToHexString(b[i]));
        }
        return resultSb.toString();
    }

    private static String byteToHexString(byte b) {
        int n = b;
        if (n < 0) {
            n += 256;
        }
        int d1 = n / 16;
        int d2 = n % 16;
        return hexDigits[d1] + hexDigits[d2];
    }

    public static String MD5Encode(String origin, String charsetname) throws Exception {
        String resultString = new String(origin);
        MessageDigest md = MessageDigest.getInstance("MD5");
        if ((charsetname == null) || ("".equals(charsetname))) {
            resultString = byteArrayToHexString(md.digest(resultString.getBytes()));
        } else {
            resultString = byteArrayToHexString(md.digest(resultString.getBytes(charsetname)));
        }
        return resultString;
    }
}
